DynamicPDF Generator for Java has several limitations, as listed here.
XFA form filling is supported only for static XFA forms with a fields entry.
The rights-enabled permission of an existing PDF document is not preserved after that document has been merged in with Merger. The rights-enabled permission acts like a digital signature and any changes to the document will invalidate it. Since the rights-enabled permission is a proprietary feature of Adobe and not part of the PDF specification, Merger is unable to revalidate it and add it back to the document.
Merger does not support the input or output of PDF documents larger than 2GB.
Merger does not support decrypting PDF documents that contain custom or unpublished algorithms (40-bit RC4 and 128-bit RC4, 128 -bit AES & 256-bit AES are fully supported).
Form flattening not supported for XFA PDFs.
Character shaping is not supported. For example, language fonts that support complex scripting or complex text layout (like Thai, Hebrew, Arabic, Indic languages, etc.) typically require character shaping.
Text extraction skips characters that are morethan 2 bytes.